Early vaccines consisted primarily of dead or attenuated pathogens, or their less virulent relatives, however the trend in vaccine development has been to move to a more defined, cleaner product with fewer side effects. Unfortunately this transition has in most cases led to a reduction in the immunogenicity of the vaccine. Over the past few years it has become clear that early vaccines exploited Pathogen Associated Molecular Patterns (PAMPs) that activated host receptors such as the Toll receptors, and that these PAMPs were key to recruitment of cells responsible for the rapid development of a robust immune response. In this application we propose to exploit the model that we developed to assay host response to mycobacterial cell wall components to elucidate how early innate responses modulate developing, acquired immune responses. This information will form the basis of a rational adjuvant development screen with the following specific aims: 1. Defining the early correlates of an effective adjuvant. We will detail the early, innate responses to vaccination and the effect of PAMPs on the development of the subsequent immune response to test the hypothesis that the inclusion of PAMPs will enhance the immune response, and facilitate identification of features critical to its efficacy. 2. Manipulation of the environment at site of inoculation. The model that we developed facilitates the manipulation of the environment at the site of inoculation through the addition of PAMPs, the inclusion of cells, or cytokines, or pro- or anti-apoptotic stimuli. This specific aim will allow experimental validation of the cellular mechanisms behind the correlates of adjuvant function that were identified in aim 1. 3. Development of a screen for new adjuvants. The longer term goal of this project is the translation of this information into an effective adjuvant-discovery screen. It is anticipated that this final aim will develop into a new grant application that will enable us to test the effectiveness of a range of microbial products for their efficacy as adjuvants. [unreadable] [unreadable]